HUMUS 77 



the Humic acid obtained from peat and one of the 

 Humic acids artificially prepared. 



Now in the ordinary decomposition of cellulose it 

 cannot be expected that Hydrochloric acid would be 

 present, but as a result of decomposition a large 

 number of organic acids would naturally be formed, 

 and tests carried out with Lactic, Acetic, Propionic, 

 Butyric, Citric, Tartaric, and Oxalic acids on 

 Sucrose, Dextrose, and Laevulose, all showed that 

 the sugars or carbohydrates went through the same 

 colour changes as had been observed with Hydro- 

 chloric acid, and gave rise both to Humic acid and 

 Humin. In other words, it was demonstrated that 

 it was reasonable to suppose that the natural process 

 by which Humic acid and the Humin were formed in 

 peat from carbohydrates had been successfully 

 imitated in the laboratory. 



While this work was in progress some interesting 

 results were obtained merely by the heating of 

 sugar, which are perhaps worth noting here, because 

 they may help to give a clear idea as to the nature 

 of Humic acid and Humin. It has long been known 

 that Sucrose fuses at a temperature of 160 C., and 

 is converted into a mixture of Dextrose and Laevu- 

 lose. If the temperature is raised to 190 C. it yields 

 a substance similar to the caramel of commerce, 

 Caramelan, and at higher temperatures it blackens, 

 becoming carbonized. When Sucrose was heated to 

 220 C. four distinct groups of substances were 

 formed. 



(i) Water-soluble caramelan; (2) a water soluble 

 substance precipitated as fine particles by Hydro* 



